SessionManager.toPreparedStatement() hangs when thread limit reached

By activing the Debug logs, we found out that we "share" Cluster among our jobs. Here is how a job is implemented:
1. In job creation:

2. At the end of a job, we perform:

In the DEBUG log, we got: (full log attached to the ticket)

So, it seems that we did not understand how to create a Cluster and/or Session and how to close them. Could you please help?

Thanks in advance.

build() creates a new cluster each time, so my guess is that your initialization code is shared among all your jobs. Can you add a log statement in there to check how many times it is called?

It is sure that we call build() for each job (cf. attached logs):

The thread qtp13890541-49 closed its cluster:

But it seems that other "clusters" used by other jobs (55, 48, 49) are closed as well:

In the log, in high activity, we got:

• 15 jobs created

• 15 "Starting new cluster with contact points" -> each job creates its own cluster with ClusterBuilder.build()

• 60 "New Cassandra host" -> OK because we have 4 nodes

• 4 "Shutting down" -> 4 cluster were shutdown at the end of the jobs

• 10 "Cluster already closed" -> 10 jobs are terminated (but could not close the cluster)

• 1 exception related to the remaining job (15 - 4 - 10 = 1) -> it causes the job hangs -> leaked resources.

Thanks again.

Hello,

We found out where is the problem: some created clusters are shared among our jobs due to incorrect job initialization.

Thanks a lot for your help!

Could you please close the ticket?
Minh